The semiconductor industry continues to have a need to access many electronic devices on a semiconductor wafer. As the semiconductor industry grows and devices become smaller and more complex, many electrical devices, most commonly semiconductor devices and on-wafer electrical interconnects, must be electrically tested, for example, for leakage currents and extremely low operating currents while the devices are in wafer form. In addition, the currents and device characteristics are often required to be evaluated over a wide temperature range to understand how temperature affects a device. Also, due to continuous and rapid changes in semiconductor technology, the size of semiconductor devices and their electrical contact pads keep getting smaller.
To effectively measure semiconductor devices in wafer form, probes are used to contact conductive pads on the surface of the wafer. These probes are, in turn, electrically connected to test instruments. Often, additional electrical interconnection components such as circuit boards make up part of the connection between the probes and test instruments. To minimize degradation of electrical measurements, the probes and interconnection components must be designed to isolate the measurement signal from external electrical interference, leakage currents through dielectric materials, parasitic capacitance, triboelectric noise, piezoelectric noise, and dielectric absorption, etc.
A typical probe card used for wafer level electrical test of semiconductor devices can include probes permanently bonded to a circuit board that is designed to interface to a particular test instrument. Changes in contact pad size, contact pad layout, or test instrument interface require the entire probe card assembly to be replaced. An alternative approach is to use a probe core that interfaces to a circuit board that, in turn, is designed to interface to a particular test instrument. Changes to the contact pad size or contact pad layout require the probe core to be replaced. Changes to the test instrument interface require the circuit board to be replaced.
Accordingly, there continues to be a need for improved semiconductor test equipment for electrically probing semiconductor devices, such as semiconductor wafers.